The present invention relates to a new and improved construction of molding machine for the fabrication of boxless casting molds.
In German patent publication No. 2,638,103 there is taught to the art a molding machine of the previously mentioned type, wherein a turnstile carries at four pivot arms a respective mold box or flask for accommodating a mold half. The pivot arms which support the mold boxes or flasks are vertically displaceable and rotatable through an angle of 180.degree. and by means of a turnstile drive these pivot arms are cyclically pivoted to successive mold stations. At a first station, coacting with an exchangeable pattern or match plate support, there is formed, by filling sand and compaction, alternately a mold lower part and a mold upper part. Following rotation of the pivot arm through 180.degree., during the next cycle the mold half is transferred by the pivot arm to the second mold station and during the next following cycle it is transferred to the third station. Both the second and third stations serve as core insert stations. Now if during the next cycle a mold lower part arrives at the fourth mold station, structured as a closing or assembly station, then the mold lower part must be brought into alignment with a mold upper part in order to complete the fabrication of the final casting mold.
To render this possible both of the pivot arms of the turnstile, carrying a mold box or flask for the mold upper part, are additionally individually pivotable about 90.degree. forwardly and backwardly within the turnstile. Now as soon as a mold lower part has arrived at the mold closing station, then the pivot arm carrying the mold upper part of the third station, with the turnstile stationary, is forwardly rocked or pivoted through 90.degree. so that both mold halves, following the rotation of the mold upper part through 180.degree., are brought into superimposed alignment with one another. So that the cyclic operation is not disturbed, it is necessary, following the ejection of the finished mold, to again rock back through 90.degree. the aforementioned pivot arm. The finished casting mold is then tranferred, by means of a transfer device, to a conveyor device.
The heretofore known molding machines are associated with a number of decisive drawbacks. The relative pivotability of both rather massive pivot arms, carrying a mold upper part, with respect to the turnstile requires two additional powerful drives. This, in turn, increases the susceptibility of the equipment to breakdown and also appreciably raises the costs thereof. Therefore, it is quite questionable whether such prior art molding machine will find acceptance in practice. Moreover, the transfer of the casting mold from the closing station to the conveyor device requires additional space.